Landmark 1957 article by Clark, Dutton and Vanderlyn which marked the start of the stereo era. I figure this is the best place to put this. It's an outstanding reference on the basis of two channel stereo- how it works, hearing, recording and reproduction. Pretty amazing that it more or less comprehensively covers many of the things we still discuss over half a century later. I rank it up there with the original Blumlein patent for both historical and academic value as well as breadth of coverage. The discussion in the appendix is worth checking out as well.